Tension press for sheet materials



July 22, 1952 J. H. PEARCE TENSION PRESS FOR SHEET MATERIALS 3 Sheets-Sheet 1 Filed June 10, 1949 JOHN (Ittomegs y J. H. PEARCE 2364, 037" TENSION PRESS FOR SHEET MATERIALS Filed Juhe 10, 1949 I 5 Sheefcs-Sheet 2 EA RcE Zinoentor attdmegs JOHN H. P

J y 22,1952 J. H. PEARCE 2,604,037.

' TENSION PRESS FOR SHEET, MATERIALS Filed June 10, 1949 "'5 Sheets-Sheet 3 Q JOHN H. PEARCE 3mm 1tor attornegs Patented July 22, 1952 OFFICE "IJENSIONQP-RESS-FOR SHEET MATERIALS I John H. Pearce, Seattle, Wash.

My'present invention relates to presses of the type that are. designed for use in the formation of sheet materials, particularly those used in the building trades, such as plywood, the various fibrous boards that are normally formed under compression and combinations of woodor wood products-and paper or plastic. My press is characterized by an arrangement which permits the application of very. high pressures but which placesthe structural elements of the press largely lintension. -In thisway, large castings and the like are avoided and steel rod stock "that is most suitablefor. sustaining large tension loads, can be used to' advantage. I

Generally my press consists of a, reenforced concrete base-in which are employed a plurality ofl.'cylinders,x-each equipped with a piston rod whichxextends upwardly and are individually joined to an upper or str'ong backsection. Gonseq'uently,'-.when the press is under use, the chief itemsi'n strain are the relatively large piston rods which exertth'e pressure and these are in tension. :In' the .past it has'been most common to use normallya si-ngle hydraulic piston of large size anclzto have a heavy cast metal base platenwhic-h was :raised and-lowered by this piston; This requires that a very-heavy upperframework beem ployed and this norrnally results in heavy castings, which are both expensive in first costand whose transportation tothe site of use is a majorproblem; and-then again; normally, cast metal can neverobtain thestrength per unit'of cross: sectional area "that can be found in alloy steelrod stock. r I

:present: press arrangement, I believe I have overcome many of the deficiencies noted in the past and provide a unit that can be largely fabricated on the job from such common items asi cement and concrete aggregate, reenforcing steel rand. cylinders, pistons, valves, screw -jacks and the vlikeyi'which .are stock items easily obtainedin ,most any locality. -Such an arrangement allows great flexibility in design and -is capable :of; producing a tension press which is quickgin operation, light and flexible in use,- and can, be built. in any si'zer'or for any pressurerequirement jThis all-can be achieved. through the -r se ,of equipment which results in a finished productthat is simpleandi-nexpensive.

,The principal object :of myxpresent invention, therefore, is to provide a tension press in which the piston rods of a plurality of hydraulic *cyl inders are employed to support, move and apply the necessary force to an upper block to bring it down into compressive c'o-action with a substantialbasemember. J v

Application June 10, 1949, Serial No. 98,215

2 Claims. (01. 100 269) A.'further object of my present invention is'to provide 1 a tension press in which instead of building a large concrete base upon which to mount a press, the press uses concrete as an integralpart of the press, and therefore, the lower elementof the press in effect forms its own foundation and does not need to be secured-in place.

A turther'object of my press is to'provide -a .cast in place lower base section and an upper or' strong. back tension member, which may be drawn toward each other by means of tension rods acting in unison, due to the fact that all the various. cylinders are piped-together and have a common source of pressure fiuid.-

.:A further object of my invention is to provide a tension press in which all the various working elements are'easily replaceable, and while this creates a device that has low initial cost, future replacement costs or servicing is reduced to a very economical operation. Further objects, advantages and capabilities will be apparent from the description and disclosure in thedrawings, or may be comprehended or are inherent in the device.

In the drawings: Figure 1 is a side elevation of a press for sheet materials made after the teachings of my present invention; a I

Figure 2 is an end elevation of my press shown in Figure 1, with certain parts broken away to better illustrate the construction; Figure 3 is a top plane view of my press, with certain parts broken away at different elevations, in order to more clearly illustrate the construction;

Figure 4 is a vertical sectional view of a typical cylinder assembly employed in my equipment, thesame-being shown as broken away in order to increase the size of the essential parts; i

Figure 5 is a cross sectional view taken along the line 5- 5 of Figure 4 and Figure 6 is a schematic diagram illustrating the fluid pressure arrangement of my press.

Referring more particularly to the disclosure in the drawings, the numeral :6 designates. one

of the hydraulic cylinders used in my device.

' I2, is the upper orstrong back section -I8.

' 3 Forming the main element of the strong back is a plurality of channels, as 20 and 22. These are arranged in pairs back to back, with holding nut 24, and lock nut 25, on the upper side of .4 top plate is provided for housing 44, as the plate 63. The plate in turn abuts under the ledge formed by portion 58 and niche 56, and secure engagement is provided by means of the screw the strong back, so as to accept the full strain 5 jack 65, there being one jack for each cylinder.

of compression when the press is working. On the underside of the strong back, a positioning nut 26, is employed. In order to assist in providing a true-flat plane which will not bend under pressure between the various supports, I

provide a platen plate 28, which is spaced away from channels 20 and 22 by a plurality of I 1* This construction is probably best beams, 30.

illustrated in Figures 1, 2 and 3. Similarly, to

provide a true plane surface, I use a lower platen is shown in considerable detail in Figures 4' and. 5.-

These units consist of the sleeve or cylinder proper 34, in which piston I6 is disposed for reciprocation. The lower end of the cylinder is preferably solid and relieved as at 36 as a matching convenience, so that piston I 6 partially overruns the cylinder wall proper, and thus any wear will be uniform throughout the whole length of the cylinder. At its upper end, the cylinder is provided with a cylinder head, 38, having the stuffing box arrangement shown at 40, through which piston rod l4 passes. The type of packing-surrounding rod I4 will have to be balanced against the maximum pressure to be retained. For extreme pressures, the so-called metallic ring packing has been found most practical. Cylinder head 38 has a sealing ring, usually of deformable metal, as 42, to insure a seal under working pressures. The cylinder head is held in place by virtue of the two part housing member 44. This member is formed in two parts, so that it can conveniently engage the cylinder and the cylinder head, after the showing of Figuresv 4 and 5.

It will be noted that the cylinder proper has a seat at 46, which has a sloping surface, as 41. Similarly, the cylinder head has a similar sloping surface, as 48. Housing 44 is machined to accommodate these bevels and when the unit is put in place and bolts 50 and 5| set up tight, ring 42 is compressed and a secure, leak-proof head is provided for the cylinder. A fluid line, 53, enters through the head. Similarly, at the lower end of the cylinder, another fluid line, 55, is employed. These serve either as pressure supply lines or exhaust lines in accordance with the valve settings and the direction of movement of thepiston.

It will be noted from Figures 1, 2 and 3 that each of the cylinders l0, seat in niches, which are U-shaped. These niches are shown in Figure 3, in plan, at 5B. A very narrow U-shaped slot is provided in the heavy ledge of concrete above the piston, as at 58, so that piston rod [4 may pass therethrough and still leave adequate strength in the material of portion 58. A very complete steel reenforcement should be employed in this concrete base and the same should be relatively rich in cement. In Figures 1 and 2, the reenforcing steel is shown in dotted lines at 60 and BI. The same is also shown in full lines in Figure 3. To serve certain conditions where very high pressures are needed or where weight is a prime consideration, a base fabricated of structural steel members, after the teachings of the top or strong back member construction, may be employed.

It will be noted from Figure 4 that a heavy As it is desirable that these cylinders be easily replaceable, this is a convenience in the initial construction of the machine and in varying the machine for different loads, entirely aside from the ease with which they can be removed if servicing is required.

5 In Figure 6 I have shown in diagrammatic form, thehydraulic pressure system which has proved to be satisfactory as a means for producing the high pressures required in a press of this order, if, for instance, plywood is to be bonded. This requires a unit pressure of approximately 15 pounds per square inch over a sheet normally 4 x 8 feet in extent and the pressure required is tremendous. To achieve this, I use, normally, a water pump, 10, which will produce reasonable pressure. It should be usually of the non-pulsating type, such as the multi-gear type pump or a centrifugal pump of either single or two stage arrangement. This I drive by any suitable power, as by the electric motor 12. Water is used in a closed circuit involving the water reservoir M, and by means of the four-way valve shown at 15, a water circuit through the pipes or tubes 1'! andlB, is provided, which acts upon the doubleacting piston within cylinder 82. In this ar-- rangement, tubes 11 and 18 may be either supply or discharge in accordance with the movement of piston 80.

Piston 8D is directlyconnected, to a high pressure piston 84, which has but a fraction of the area of piston 80. Piston 84 operates in the double-acting cylinder 85 and consequently. again, the high pressure pipes 81 and 88, may be either supply or discharge, in accordance with the setting of valve 90. In thisI prefer to use a closed oil circuit with a reserve reservoir 92. There are a number of commercial oils that serve this purpose, although for certain uses, a mixture of water, alcoholand a small amount of sperm oil, proves very satisfactory. This, following the proportions used in recoil cylinders of cannon, hydraulic jacks and the like. ,In accordance with the setting of valve 94,; which is again a fourway valve, the high pressure fluid is forced through either tube 53 or 55, these being led respectively to the upper portion of cylinder l0 and to the lower portion of the same. It will be noted from Figure 6 that the cylinder units are piped in parallel, so that the same pressure will be present in each cylinder. This is particularly true in the manner in which these machines are used, as considerable time is available to build up and distribute the pressure. When so arranged, it will be apparent, it is believed,'that each of thevarious piston rods, [4, will have the same force applied to it, whether directed to raise the piston rod or retract'it, as'occurs in the pressing operation. Now it has been found that with a substantial base as indicated in the drawings by reference character [2, and by means of the platen platesZB and -32, that very uniform pressure can be appliedto relatively large sheet materials. Further, the system is a very workable one, in that by having a control handle on valve 94, a nicety of movement can be effected to either raise the upper pressure member or "'strong back I8, or to bring it down upon a stack of sheet stock for the pressing operation.

It is believed that it will be clearly apparent from the above description and the disclosure in the drawings that the invention comprehends a novel construction of a tension press for sheet materials.

Having thus disclosed thev invention, I claim:

1. A tension press for sheet materials, consisting of: a lower base section; an upper press strong back; a, plurality of double-acting press cylinders removably secured in a vertical arrangement within niches in said lower base section; double-acting press pistons disposed for reciprocation in said cylinders; piston rods 0peratively connecting said pistons and said upper press strong back; said lower base section being formed of re-enforced concrete having a ledge portion disposed above each cylinder; jacks adapted to seat the upper portion of each cylinder firmly against said ledge portion; said upper press strong back being fabricated from structural steel shapes.

2. A tension press for sheet materials, consisting of z a, fabricated lower base section; a fabricated upper press section; a plurality of doubleacting press cylinders secured in a vertical arrangement within opposite sides of said lower base section; double-acting press pistons reciprocatively disposed in said cylinder; piston rods operatively connecting said pistons and said upper press section; said cylinders having a flange at their upper ends with a beveled lower surface; a piston head having a peripheral extension with a beveled upper surface; a clamp, split vertically and having an annular groove adapted to engage the beveled surfaces of said cylinder and said piston head and hold said head securely to said cylinder; 2. high pressure hy- I draulic system to provide fluid to said cylinders; tubing adapted to lead high pressure fluid, from said high pressure systemto each end of said press cylinders; and valve means adapted to selectively control the direction of fluid flow to said press cylinders.

JOHN H. PEARCE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,373,055 Cohill Mar. 29, 1921 1,808,244 McCullough June 2, 1931 1,996,772 MacKensie' Apr. 9', 1935 1,999,249 Meyercord Apr. 30, 1935 2,148,704 Merritt Feb. 28, 1939 2,200,998 Schnuck May 14, 1940 2,296,072 Tucker Sept. 15, 1942 2,484,908 Purcell Oct. 18, 1949 2,487,792 Custer Nov. 15, 1949 

